Uptake and distribution of Zn⁶⁵ in the coho salmon egg (Oncorhynchus kisutch)

1. Zinc uptake and distribution in the developing coho salmon egg was measured using radioisotope tracer techniques.

2. The uptake was affected by pH, temperature, Cu²⁺, 2,4-fluorodinitrobenzene and the azo dye, malachite green; but not by azide ion or 2,4-dinitrophenol.

3. About 70 per cent of the total accumulated zinc was bound, rather firmly, to the chorion; about 26 per cent was found in the perivitelline fluid, about 2 per cent in the yolk, and about 1 per cent in the embryo.

4. Temperature, pH, inhibitor and kinetic studies indicated that zinc uptake involves physicochemical sorption to the chorion together with passive diffusion into the yolk and embryo.